<script>
  function setDPI() {
    if (window.testRunner) {
      testRunner.waitUntilDone();
      testRunner.setBackingScaleFactor(1.5, function() { testRunner.notifyDone(); });
    }
  }
</script>
<body onload="setDPI();">
  <div style="resize:both; overflow:scroll; width:200px; height:200px;">
    The resize handle should grow with DPI.
  </div>
</body>